PubMed Health⌕ Search

Biomedical subjects

F Bojsen-Møller

Publications and source records attributed to F Bojsen-Møller.

At least 19 recordsLinked to original sources
PubMed2002

Arthroscopy of the proximal interphalangeal joints of the finger.

Cadaveric studies were carried out to evaluate the technique, portals and possible indications for arthroscopy of the proximal interphalangeal joints of the finger. We suggest horizontal placement of the hand instead of using a traction tower, as it is important to be able to flex the joint freely. The recommended arthroscopic portals are either between the central slip and the lateral bands of the extensor mechanism or between the lateral band and the collateral ligament. A blunt technique of introduction is used to avoid iatrogenic cartilage damage and possible digital nerve injury.

Adult↗
PubMed2000

MRI of the plantar structures of the foot after falanga torture.

Falanga is an ancient form of punishment or torture but is still commonly reported by our refugees. The late result of caning the heel and ball of the foot is a chronic painful condition with few clinical signs. The aim of the present study was to assess, by MRI, possible morphologic characteristics of the heel and ball of the foot, related to falanga and pain in correlation to clinical findings. Magnetic resonance imaging of the foot was obtained in 12 victims exposed to falanga torture and 9 healthy volunteers. Sagittal T1-weighted spin-echo images (TR 616-840 ms, TE 20 ms), T2-weighted spin-echo images (TR 1900 ms, TE 90 ms), and short tau inversion recovery (STIR) images (TR 1200 ms, TE 15 ms, TI 100 ms) were performed. The central portion of the plantar aponeurosis was generally significantly thicker in victims exposed to falanga torture as compared with that of controls (P < 0.05). In all except one of the victims, MRI demonstrated two layers of the thickened plantar aponeurosis: a deeper portion with normal homogeneous low signal intensity (SI) appearance, and a superficial layer with characteristic areas of mixed SI on both T1- and T2-weighted images. There were no signs of chronic muscular compartment syndromes, and the thickness of the plantar pad did not differ between the two groups. Magnetic resonance imaging may demonstrate morphologic characteristics of the plantar aponeurosis which may confirm falanga torture. Further imaging with more specific sequences is warranted to demonstrate the supposed injuries in the compartmental fat tissue chambers and the vascularity of the ball pad of the foot.

Adult↗
PubMed2000

Comparison of muscle sizes and moment arms of two rotator cuff muscles measured by ultrasonography and magnetic resonance imaging.

OBJECTIVE: The purpose was to investigate ultrasound (US) and anthropometry (AN) as valid alternatives to magnetic resonance imaging (MRI) regarding muscle size characteristics of two rotator cuff muscles. METHODS: Eight healthy females (age 27-54 yrs.) went through MRI and US scannings and AN measurements, where muscle thickness, cross-section area (CSA), moment arm, muscle length and width were measured on supraspinatus and infraspinatus muscle. RESULTS: The agreement between the methods was very satisfactory for CSA, and satisfactory for muscle thickness, moment arm, muscle length and width, with a mean difference below 2 mm in thickness and below 5 mm in muscle length and width. Volume could be estimated satisfactory in supraspinatus muscle, but not in infraspinatus muscle, where volume had to be calculated from thickness, length and width. As a significant relation was found in the MRI measurements between thickness and CSA, thickness measurements may replace CSA in inaccessible muscles. CONCLUSIONS: US was a valid method in measuring CSA, muscle thickness and moment arm. Combined with anthropometric measures of muscle length and width, volume can be calculated, which is important when defining the physiological cross-sectional area and muscle function. Further development and validation of the method is needed, however.

Adult↗
PubMed2000

Antagonist muscle coactivation during isokinetic knee extension.

The aim of the present study was to quantify the amount of antagonist coactivation and the resultant moment of force generated by the hamstring muscles during maximal quadriceps contraction in slow isokinetic knee extension. The net joint moment at the knee joint and electromyographic (EMG) signals of the vastus medialis, vastus lateralis, rectus femoris muscles (quadriceps) and the biceps femoris caput longum and semitendinosus muscles (hamstrings) were obtained in 16 male subjects during maximal isokinetic knee joint extension (KinCom, ROM 90-10 degrees, 30 degrees x s(-1)). Two types of extension were performed: [1] maximal concentric quadriceps contractions and [2] maximal eccentric hamstring contractions Hamstring antagonist EMG in [1] were converted into antagonist moment based on the EMG-moment relationships determined in [2] and vice versa. Since antagonist muscle coactivation was present in both [1] and [2] a set of related equations was constructed to yield the moment/EMG relationships for the hamstring and quadriceps muscles, respectively. The equations were solved separately for every 0.05 degrees knee joint angle in the 90-10 degrees range of excursion (0 degrees = full extension) ensuring that the specificity of muscle length and internal muscle lever arms were incorporated into the moment/EMG relationships established. Substantial hamstring coactivation was observed during quadriceps agonist contraction. This resulted in a constant level of antagonist hamstring moment of about 30 Nm throughout the range of motion. In the range of 30-10 degrees from full knee extension this antagonist hamstring moment corresponded to 30-75% of the measured knee extensor moment. The level of antagonist coactivation was 3-fold higher for the lateral (Bfcl) compared to medial (ST) hamstring muscles The amount of EMG crosstalk between agonist-antagonist muscle pairs was negligible (Rxy2<0.02-0.06). The present data show that substantial antagonist coactivation of the hamstring muscles may be present during slow isokinetic knee extension. In consequence substantial antagonist flexor moments are generated. The antagonist hamstring moments potentially counteract the anterior tibial shear and excessive internal tibial rotation induced by the contractile forces of the quadriceps near full knee extension. In doing so the hamstring coactivation is suggested to assist the mechanical and neurosensory functions of the anterior cruciate ligament (ACL).

Adult↗
PubMed2000

Anterior cruciate ligament injury in indoor ball games.

Three videorecorded incidents of knee injuries inflicted during indoor ball games are reported. Injuries and especially anterior cruciate ligament ruptures seemed to be triggered in varus loaded knees by femural external rotation, or in valgus loaded knees by femural internal rotation with the pivot shifted to the lateral femurotibial compartment. The observations suggest that it may be to the players' advantage to be trained in not letting their knees sag medially or laterally during side-stepping or sudden changes in speed.

Anterior Cruciate Ligament Injuries↗
PubMed2000

Passive tensile stress and energy of the human hamstring muscles in vivo.

The present study measured passive resistance to stretch in the hamstring muscles during a standardized stretch maneuver to estimate tensile forces and energy of the individual hamstring muscles in 7 flexible and 6 inflexible persons defined according to joint range of motion. Using a dynamometer, knee joint moment was measured during slow passive knee extension to a maximal angle (dynamic phase) followed by a 90-s static phase. Cross-sectional areas (CSA) of the separate hamstring muscles were obtained with magnetic resonance (MR) imaging. Mathematical modeling was used to calculate instantaneous muscle length and joint moment arm for each muscle. Subsequently, passive muscle tension (N/cm2) was calculated based on moment arm lengths, knee joint moments, and CSA. Maximal tolerated joint angle was greater in flexible (delta1.30+/-0.06 rad) than inflexible (delta0.84+/-0.06 rad) subjects, P<0.01. The peak tension at maximal angle was greater in flexible (81.8+/-12.5 N/cm2) than inflexible subjects (29.3+/-4.1 N/ cm2), P<0.001. For the separate muscles the overall change in muscle length (delta cm) and moment arm (delta cm) differed between groups, P<0.01. Similarly, muscle stiffness (delta tension/delta muscle length) was greater in flexible than inflexible subjects in the final 3 cm, P<0.01, and in the final 20% of length change, P<0.01. Absorbed energy (mJ/cm2) was greater in flexible than inflexible subjects in the final 40% of length change, P<0.05. These data show that flexible persons can attain a greater angle of stretch with an accompanying greater tensile stress and energy than inflexible persons due to an apparent greater tolerance to the externally applied load, and larger change in moment arm. The obtained stress data appear to be in the toe region of a 'classical' stress-strain curve, and energy rather than stiffness may therefore be more appropriate to analyze during the stretch procedure.

Adult↗
PubMed2000

Tarsal functions, movement, and stabilization mechanisms in foot, ankle, and leg performance.

The authors investigated the function of the tarsus and the skeletal segments of the foot in terms of the biomechanical significance of the individual links of the foot-ankle-leg complex. A performance model based on pressure-washed trabecular systems and the interface of the different segments making up the articular foot skeleton is presented and discussed. The biomechanical influence of these segments on each other and on their appendicular companion bones is assessed, and an explanation of their function is provided.

Ankle↗
PubMed1999

Choice of jumping strategy in two standard jumps, squat and countermovement jump--effect of training background or inherited preference?

Six male subjects, three professional ballet dancers and three elite volleyball players, performed maximal vertical jumps from 1) a static preparatory position (squat jump), 2) starting with a countermovement (countermovement jump) and 3) a specific jump for ballet and for volleyball, respectively. The jumps were recorded on highspeed film (500 Hz) combined with registration of ground reaction forces, and net joint moments were calculated by inverse dynamics. The purpose was to investigate the choice of strategy in two standard jumps, squat jump and countermovement jump. The volleyball jump was performed with a sequential strategy and the ballet jump was performed with a simultaneous strategy. In the two standard jumps, the choice of strategy was individual and not related to training background. This was additionally confirmed in a test of seven ballet dancers and seven volleyball players.

Biomechanical Phenomena↗
PubMed1998

Post-mortem ultrasonographic assessment of the anterior glenoid labrum.

OBJECTIVE: The purpose of this study was to investigate the identification of the anterior glenoid labrum with ultrasonography. METHODS: Twelve cadaveric shoulders from subjects 74 to 85 years of age were examined by ultrasonography. Under ultrasonographic guidance, a small amount of dye was injected on the structure believed to be the anterior glenoid labrum, whereafter the shoulders were dissected. RESULTS: In 11 shoulders the dye was found in close relation to the glenoid labrum. Comparing the labrum to a watch face numbered clockwise in the left shoulder, and counter clockwise in the right, the part seen was located between 1 and 5 o'clock. Signs of degeneration were found in six labra by ultrasonography and verified by blindfolded dissection. CONCLUSIONS: Ultrasonography can identify the anterior glenoid labrum and distinguish degenerated from normal labra.

Aged↗
PubMed1998

A biomechanical evaluation of cyclic and static stretch in human skeletal muscle.

The short term effect of static and cyclic stretch paradigms on stiffness and maximal joint range of motion was examined in 12 recreational athletes. To assess flexibility, joint range of motion and resistance to stretch were measured using a dynamometer during a passive stretch of the hamstring muscle group to the point of pain. The recorded torque-angle curve allowed for identification of maximal joint range of motion and calculation of passive muscle-tendon stiffness and energy. Three flexibility assessments (stretch 1 - 3), each 10 min apart, were administered to each leg. A 90 s static stretch and 10 cyclic stretches were performed after the second stretch on the left and right side, respectively. Stiffness in a common range for stretch 1 - 3 was unchanged on both the left and right side. However, on the left side (static stretch) there was a significant effect of flexibility assessment (stretch 1 - 3) (p < 0.0001) with an increased maximal joint angle (p < 0.01) and maximal stiffness (p < 0.05) between all three stretches. Similarly, on the right side (cyclic stretches) there was a significant effect of flexibility assessment (p < 0.0001) with an increased maximal joint angle between stretch 1 and 3 (p < 0.01) and maximal stiffness (p < 0.05) between all stretches. During the static stretch passive torque declined 35+/-4% (p < 0.001). During the cyclic stretches passive energy and hysteresis both declined 17% (p < 0.05) while stiffness increased 12% (p < 0.05). The results of the present study demonstrate that static and cyclic stretching, as it is commonly performed by athletes, increases joint range of motion by increasing stretch tolerance while the viscoelastic characteristics of the muscle remain unaltered.

Adult↗
PubMed1995

The influence of tendon Youngs modulus, dimensions and instantaneous moment arms on the efficiency of human movement.

The purpose of the study was to examine the influence of passive tendon work on the gross mechanical efficiency of human whole body movement. Seven male subjects participated in the study. They performed repetitive jumps (like skipping) of three different intensities. Metabolic costs and work rates were recorded to obtain mechanical efficiencies. Net joint moments were calculated from film recordings using inverse dynamics. A general stress-strain relationship for tendons was modelled using a quadratic function, including Youngs elastic modulus of tendon tissue and tendon dimensions. Instantaneous tendon moment arms for the largest leg extensor muscles (m. triceps surae and m. quadriceps femoris) were calculated using joint angle-moment arm transfer functions obtained from the literature (cadaver studies) and the tendon work was calculated from the net joint moments. Gross efficiency values of 0.65-0.69 and efficiency values of 0.77-0.80 at the approximate level of the muscle-tendon complexes were observed. The tendons performed 52-60% of the total work. The enhancement of the muscle-tendon efficiency over the maximal theoretical efficiency of the contractile machinery (0.30) could exclusively be explained by the contribution of the tendon work. A clear negative relationship between repetitive jumping with high mechanical efficiency and running economy at 12 km h-1 was found. Using model calculations the gross efficiency and the muscle-tendon efficiency were shown to be sensitive to tendon Youngs modulus, dimensions and moment arms. The efficiencies were most sensitive to changes in the tendon moment arms. A 10% decrease in tendon moment arms resulted in a 13% increase in the gross efficiency. Optimization or minimisation of the mechanical efficiency by changing the tendon variables 5% was followed by changes in mechanical efficiency of +14% and -10%, respectively.

Adult↗
PubMed1995

The influence of strength training, swim training and ageing on the Achilles tendon and m. soleus of the rat.

Different age groups of male Wistar rates were submitted to intense strength training, swim training or no training. It was found that the tetanic of the m. soleus decreased with age. This was counteracted by strength training, whereas swim training had no effect on tetanic tension. Force at ultimate failure and yield point in the Achilles tendon decreased with age, but were not influenced by strength training. Swim training, on the other hand, appeared to compensate for the ageing process in the tendon. We conclude that tendon strength decreases with age and that tendon strength does not reflect muscle strength. The absolute tensile strength of tendons appears to be influenced by physical activity of endurance-type exercise. However, it is not known whether the tissue responds to the number of mechanical muscle contractions or physiological factors connected with endurance training. Although it is questionable to extrapolate from the rat to humans, it is speculated that intensive muscle strength training should be accompanied by endurance exercise in order to prevent the muscles from damaging connective tissue structures, such as the tendons and ligaments.

Achilles Tendon↗
PubMed1995

Bone-on-bone forces during loaded and unloaded walking.

Joint moments and bone-on-bone forces in the ankle, knee and hip joint were studied in 7 healthy male subjects during unloaded and loaded walking. The subjects walked across a force platform while they were filmed at 200 Hz. Loaded walking was examined at 10 and 20 kg load carried symmetrically in the hands. Peak joint moments and peak bone-on-bone forces increased from unloaded to loaded walking for the ankle and hip joint (p < 0.05). The lowest bone-on-bone forces were found at the ankle joint (3,318 +/- 390 N) during unloaded walking and the highest at the hip joint (6,399 +/- 1,517 N) during 20 kg loading. Expressed relative to body weight (BW) these values corresponded to 4.2 +/- 0.50 and 8.0 +/- 1.78 BW). However, the individual values showed that 2 of the 7 subjects differed remarkably from the other 5, especially with respect to the hip joint loadings. During loaded walking (20 kg) these 2 subjects showed 14.4 and 15.1 BW peak compression force in the hip joint while the remaining subjects were all below 6.3 BW, which could be explained by the 2 subjects' low ankle joint moments and higher knee and hip joint moments. Apparently, a total 'leg moment' formed by the three major joints is required to support the body and maintain the locomotion, although the relative contribution from each joint can differ among individuals. The peak joint moments were the most dominant contributor to the peak bone-on-bone forces. Therefore, it is concluded that interindividual differences in walking style can lead to pronounced differences in peak bone-on-bone forces. It remains unclear how these interindividual differences are related to joint degradation.

Adult↗
PubMed1994

Evaluation of direct and indirect inguinal hernia by computed tomography.

The importance of venous distension of the pampiniform plexus in the prevention of inguinal hernia was evaluated. Functional closure of the inguinal canal was investigated by computed tomography during a Valsalva manoeuvre in a normal individual and 12 men with unilateral inguinal herniation, one of whom had previously undergone herniorrhaphy. Thus, 13 normal canals were evaluated along with five with direct and seven with indirect hernia. In all normal canals a rise in intra-abdominal pressure increased the cross-sectional area of the part of the pampiniform plexus located in the medial end of the canal, thereby filling the empty space and preventing herniation. In the lateral part the plexus was compressed against the external aponeurosis by the fascia transversalis in a valve-like fashion. In cases of direct inguinal herniation the distended pampiniform plexus was displaced by the hernia sac during the Valsalva manoeuvre, but in indirect hernia impaired swelling of the pampiniform plexus was seen. It is suggested that this observation could help to explain the normal mechanism of closure of the inguinal canal.

Adult↗
PubMed1990

Shock absorbing material on the shoes of long leg braces for paraplegic walking.

A study was designed to evaluate if shock absorbing material (ethyl vinyl acetate (EVA)) on the shoes of long leg braces could decrease the accelerations and consequent shock forces transmitted through the leg and brace during paraplegic walking. Six male paraplegics (26-55 years old) took part, four using a "swing-to" and two a "swing-through" technique when walking. Recordings comprised accelerometry of leg and brace, force platform measurement, and still photography of the trajectories of the leg segments. Each experimental condition was tested three times with a coefficient of variation (CV) for the measurements ranging from 5-22%. Compared to hard heels, shoes equipped with 20 mm EVA soles decreased the acceleration amplitude in the first 10 msec as well as at maximum for shoe-to-ground contact. With the accelerometer at the malleolus reduction of the amplitude averaged 22% and 12% respectively, and 35% and 21% respectively with the accelerometer on the caliper (p: 0.03-0.1). In a second trial the two "swing-through" walkers had new shoes made with a 10 mm thick EVA heel built in. After 3 months of walking with these shoes tests were carried out with the accelerometer attached to the malleolus both when the new and the former shoes were put on the calipers. CV for these measurements were 15-24%. It was found that the new shoes decreased the amplitudes by up to 62% and 26% on average (all p less than 0.01). The experimental subjects indicated that the EVA soles/heels gave a more comfortable and silent walk, e.g. the "bump" transmitted up through the body to the head diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Functional closure of the femoral canal revealed by computed tomographic scanning.

The lacuna vasorum contains, as well as the external iliac vessels, a space called the femoral canal which allows pulsation and other changes in the diameter of the two vessels. The canal is closed by a connective tissue septum which is too weak to prevent a herniation alongside the vessels. The functional closure of the canal was investigated by artificial augmentation of the intraluminal pressure of the vein in five specimens and by computed tomographic (CT) scanning during a Valsalva manoeuvre in ten normal persons. In the abdomen the intraluminal and extraluminal pressures are raised in parallel, with no consequence for the diameter of the vessels. In the area of the lacuna vasorum the intravenous pressure is conveyed down to the first competent valve which is located 0.5 cm distal to the inguinal ligament, while the extraluminal pressure is reduced to normal. At each rise of the intra-abdominal pressure the vein will therefore bulge and exactly fill the empty space of the femoral canal thus preventing herniations by an on-demand mechanism. By CT scanning it was found that the vein in the femoral canal increased its diameter 2.5-3.0 times during the Valsalva manoeuvre.

Abdomen↗
PubMed1989

The influence of initial posture on the sit-to-stand movement.

Head movements, ground reaction forces and electromyographic activity of selected muscles were recorded simultaneously from two subjects as they performed the sit-to-stand manouevre under a variety of conditions. The influence of initial leg posture on the magnitude of the various parameters under investigation was examined first. A preferred initial leg posture resulted in smaller magnitudes of head movement and ground reaction forces. EMG activity in some muscles, trapezius and erector spinae, decreased, while in others, quadriceps and hamstrings, it increased in the preferred leg posture. The decreases seen correlate with reductions in head movement observed. The effect of inhibiting habitual postural adjustments of the head and neck, by comparing "free" and "guided" movements was also examined. In guided movements there are significant reductions in head movement, ground reaction forces and EMG activity in trapezius, sternomastoid and erector spinae. It would appear that both initial leg posture and the abolition of habitual postural adjustment have a profound influence on the efficiency of the sit-to-stand manouevre. This preliminary study high-lights the practical importance of head posture in the diagnosis and treatment of movement disorders, as well as in movement education.

Humans↗